marked by the trees and brush that fill them in many places. It appears that a well-developed growth of trees is to be found only along the river banks in this region and the growth in the abandoned channels is probably due to the fact that in flood time there is much seepage of water into these old channels if not an actual overflow from the present course of the stream. At the bottom of the picture is to be seen the recently made land under cultivation. The fields appear striated and checkered, obscuring the concentric banding. The illustration is from a mosaic made up at Camp Benning near-by of many photographs matched together, hence there are certain differences in shade due to dark and light prints. Scale, about 1:38,000.] [Illustration: FIG. 35--Map of the same area shown in Fig. 34 enlarged from the corresponding sections of the Columbus and Seale, Ga.-Ala., topographic sheets, 1:62,500, published by the U. S. Geological Survey. The cross section at the bottom lies along the line indicated on the map and extends somewhat beyond the right border of the map. The section shows between the hills the broad lowland over which the Chattahoochee River has meandered. Scale, 1:38,000.] [Illustration: FIG. 36--A river channel in the Great Plains. The Red River northeast of Wichita Falls, Tex., as photographed from a height of 8,000 feet, September 12, 1918. Between the bluffs is seen the dark-colored water of the braided stream flowing on a broad sandy bed more than a mile wide, which is completely covered with water only at flood time. The river forms the Texas-Oklahoma boundary, and frequent changes in the position of the channel during periods of high water make the exact position of the interstate boundary uncertain and give rise to disputes and litigation over the ownership of land. North of the river (top of figure) to the right are sand dunes with a sprinkling of trees and bushes; in the middle of the channel there is an island of light-colored sand. The stream channel bites sharply into the southern bluff, which is cut by many strong gulches. Across the river is the familiar sand flat built of the material washed downstream at flood time and spread out by the subsiding water. The channel at this point shows the changes that have taken place in the position of the stream and, where the stream crosses the sandy floor, affords an example of braiding. Scale, about 1:23,000.]